Apparatus for conveying rounded can body blanks to a welding unit

Abstract

A conveying apparatus feeds can body blanks to a welding unit with the longitudinal edges of the can body blanks even, without being offset in the longitudinal direction. The apparatus includes a centrally disposed revolving device (5; 5'; 5") which serves as a transport unit for the can body blanks (1). Rockers (18) are connected by means of swivel axes (5b) to serve as pusher dogs. Each rocker (18) has two feed pins (18c, 18d) at its front end facing the direction of transport. In the pushing position, the feed pins simultaneously contact the rear edge of a can body blank (1) on either side of the longitudinal edges. Each of the rocker arms is provided with a control arm which extends past the swiveling axis and which has a control surface.

What we claim is: 
     
       1. An apparatus for conveying rounded can body blanks in a direction of transport to a welding unit, the blanks having front and rear edges and longitudinal edges between the front and rear edges, the welding unit connecting the longitudinal edges of the blanks with welded seams, said apparatus comprising: a rail extending in the direction of transport, the rail having a predetermined width and having sides with longitudinal grooves to guide the longitudinal edges of the blanks; and   transport unit means adjacent the rail for moving the blanks in the direction of transport, the transport unit means having a pusher dog section in which the transport unit means comes into contact with the blanks, the transport unit means including a single revolving device having a periphery,   a plurality of rocker elements, each having two feed pins which are connected to one another via the respective rocker element and which are spaced apart by a distance greater than the width of the rail, each feed pin having a pusher dog surface for engagement with the rear edges of the blanks, each rocker element additionally having a control arm with a control surface,   means for mounting the rocker elements on the revolving device so that the rocker elements are movable about respective swiveling axes that are transverse to the direction of transport, the rocker elements being uniformly distributed about the periphery of the revolving device at positions such that the distance between the pusher dog surfaces of one rocker element and the pusher dog surfaces of an adjacent rocker element is greater than the length of a can body blank, and   a guide track which is slidably engaged by the control surfaces of the rocker elements,     wherein the transport unit means brings the pusher dog surfaces of the rocker elements into contact with the rear edges of the blanks during entry of the blanks into the pusher dog section of the transport unit means, with the pusher dog surfaces of a rocker element being disposed on both sides of the rail and simultaneously pushing against the rear edge of a blank adjacent the longitudinal edges of the respective blank, and wherein the guide track has a portion which is configured to support the rocker elements so that the pusher dog surfaces maintain a predetermined orientation with respect to the direction of travel as the rocker elements exit the pusher dog section of the transport unit means.   
     
     
       2. The apparatus of claim 1, wherein the revolving device is positioned with respect to the welding unit so that the transport unit means moves a blank far enough for a portion of the respective seam to be welded. 
     
     
       3. The apparatus of claim 1, wherein each rocker element has a side and an angular configuration when viewed from the side, each rocker element additionally having a top and a U-shaped configuration when viewed from the top while the respective rocker element is moving in the direction of travel, the U-shaped configuration including arms which point opposite the direction of travel. 
     
     
       4. The apparatus of claim 3, wherein the distance between the feed pins of a rocker element is smaller than the distance between the arms of the respective rocker element. 
     
     
       5. The apparatus of claim 1, further comprising a support arm which extends in the direction of travel, the rail being connected to the support arm, and feed chain drive mechanisms on both sides of the support arm, the feed chain drive mechanisms having pusher dog teeth which project to positions for engagement with the rear edges of the blanks, and wherein the transport unit means further comprises means for adjusting the revolving element in relation to the feed chain drive mechanisms so that the pusher dog surfaces of a rocker element corresponding to a pair of pusher dog teeth have a predetermined advance in the direction of transport, the means for adjusting including a shifting unit. 
     
     
       6. The apparatus of claim 5, wherein the predetermined advance is between about one millimeter and about two millimeters. 
     
     
       7. The apparatus of claim 5, wherein the feed chain drive mechanisms extend in the direction of transport and pass adjacent the welding unit and adjacent the revolving device. 
     
     
       8. The apparatus of claim 5, wherein the transport unit means has a discharge region where the rocker elements exit the pusher dog section of the transport section, wherein the feed chain drive mechanisms extend in the direction of transport and pass adjacent the welding unit, and wherein the feed chain drive mechanisms have rear end segments that are disposed in the discharge region of the transport unit means. 
     
     
       9. The apparatus of claim 1, further comprising first and second pairs of friction rollers to engage blanks moving in the direction of transport, each pair including a respective top roller that is driven, the pairs of rollers being disposed on opposite sides of the welding unit and the first pair of rollers being disposed between the transport unit means and the welding unit, and a continuously adjustable coupling for the driven roller of the first pair. 
     
     
       10. The apparatus of claim 9, wherein the velocity of the rocker elements in the direction of transport is larger than the circumferential velocity of the rollers by approximately the percentage that the distance between rocker elements exceeds the length of the blanks. 
     
     
       11. The apparatus of claim 1, wherein the revolving device comprises an endless chain, wherein the rocker elements have arms, and wherein the means for mounting the rocker elements on the revolving device comprises bearing blocks connected to the chain, the arms of the rocker elements being pivotably supported on the bearing blocks. 
     
     
       12. The apparatus of claim 1, wherein the revolving device comprises a rotating disk, wherein the rocker elements have arms, and wherein the means for mounting the rocker elements on the revolving device comprises means for pivotably connecting the arms to the disk. 
     
     
       13. The apparatus of claim 1, further comprising a support arm extending in the direction of travel, the rail being connected to the support arm. 
     
     
       14. The apparatus of claim 1, wherein the transport unit means is disposed above the can body blanks. 
     
     
       15. The apparatus of claim 1, wherein the pusher dog surfaces of the rocker elements are disposed approximately perpendicular to the direction of travel when the pusher dog surfaces are brought into contact with the rear edges of the blanks. 
     
     
       16. The apparatus of claim 1, wherein the predetermined orientation maintained by the pusher dog surfaces as the rocker elements exit the pusher dog section is approximately perpendicular to the direction of travel. 
     
     
       17. The apparatus of claim 1, wherein each rocker element has first and second ends, the feed pins being provided at the first end and the control surface being provided at the second end, and wherein the swivel axis for the respective rocker element is positioned between the first and second ends.